Prescription weight loss drugs are often frowned upon, but if you struggle with your weight and feel like nothing else is working it might be worth asking your doctor about. Whether it’s orlistat, phentermine, or another option, the medications on this list may be the answer you need. Here’s a look at five popular prescription weight loss drugs currently available in the United States.
The six most commonly prescribed Weight Loss Drugs are Orlistat, Phentermine, Sibutramine, Lorcaserin Hydrochloride, Naltrexone Hydrochloride, and Liraglutide Acetate. All of these drugs have side effects so it is important to discuss them with your healthcare professional before taking them.
Should You Take a Weight Loss Pill
Eating less and moving more are the basics of weight loss that lasts. For some people, prescription weight loss drugs may help.
You’ll still need to focus on diet and exercise while taking these drugs, and they’re not for everyone.
Doctors usually prescribe them only if your BMI is 30 or higher, or if it’s at least 27 and you have a condition that may be related to your weight, like type 2 diabetes or high blood pressure.
The medication semaglutide (Wegovy) received FDA approval for treatment of obesity in 2021. More common prescription weight loss drugs which have been in use longer include: liraglutide (Saxenda), naltrexone-bupropion (Contrave), orlistat (Alli, Xenical), phentermine (Adipex-P, Ionamin, Pro-Fast), and phentermine-topiramate (Qsymia).
Before you get a weight loss drug prescription, tell your doctor about your medical history. That includes any allergies or other conditions you have; medicines or supplements you take (even if they’re herbal or natural); and whether you’re pregnant, breastfeeding, or planning to get pregnant soon.
How it works: Liraglutide is a higher dose of the type 2 diabetes drug Victoza. It mimics an intestinal hormone that tells the brain your stomach is full.
Approved for long-term use? Yes.
Side effects: Nausea, vomiting, diarrhea, constipation, and low blood pressure. Serious side effects can include raised heart rate, pancreatitis, gallbladder disease, kidney problems, and suicidal thoughts. Liraglutide has been shown in studies to cause thyroid tumors in animals, but it is not yet known if it can cause thyroid cancer in humans.
What else you should know: If you don’t lose 4% of your weight after 16 weeks of taking Liraglutide, your doctor may tell you to stop taking it, because it’s unlikely to work for you, the FDA says.
Naltrexone HCl and bupropion (Contrave)
How it works: Contrave is a combination of two FDA-approved drugs, naltrexone and bupropion, in an extended-release formula. Naltrexone is approved to treat alcohol and opioid dependence. Bupropion is approved to treat depression, seasonal affective disorder, and help people stop smoking.
Approved for long-term use? Yes.
Side effects: The most common side effects include nausea, constipation, headache, vomiting, dizziness, insomnia, and dry mouth. Contrave has a boxed warning about the increased risk of suicidal thoughts and behaviors associated with bupropion. The warning also notes that serious neuropsychiatric issues linked to bupropion have been reported. Contrave can cause seizures and must not be used in patients who have seizure disorders. The drug can also increase blood pressure and heart rate.
What else you should know: If you don’t lose 5% of your weight after 12 weeks of taking Contrave, your doctor may tell you to stop taking it, because it’s unlikely to work for you, the FDA says.
How it works: Blocks your body from absorbing about a third of the fat you eat.
When a doctor prescribes orlistat, it’s called Xenical. If you get it without a prescription, it’s called Alli, which has half of Xenical’s dose.
Approved for long-term use? Yes.
Side effects include abdominal cramping, passing gas, leaking oily stool, having more bowel movements, and not being able to control bowel movements.
These side effects are generally mild and temporary. But they may get worse if you eat high-fat foods.
Rare cases of severe liver injury have been reported in people taking orlistat, but it’s not certain that the drug caused those problems.
What else you should know: You should be on a low-fat diet (less than 30% of your daily calories from fat) before taking orlistat.
Also, take a multivitamin at least 2 hours before or after taking orlistat, because the drug temporarily makes it harder for your body to absorb vitamins A, D, E, and K.
Orlistat is the only drug of its kind that’s approved in the U.S. All other prescription weight loss drugs curb your appetite, including the following.
How it works: Curbs your appetite.
Your doctor may prescribe this under the names including Adipex or Suprenza.
Approved for long-term use? No. It’s approved for short-term use (a few weeks) only.
Side effects can be serious, such as raising your blood pressure or causing heart palpitations, restlessness, dizziness, tremor, insomnia, shortness of breath, chest pain, and trouble doing activities you’ve been able to do.Less serious side effects include dry mouth, unpleasant taste, diarrhea, constipation, and vomiting.
As with some other appetite suppressants, there’s a risk of becoming dependent upon the drug.
Don’t take it late in the evening, as it may cause insomnia.
If you take insulin for diabetes, let your doctor know before you take phentermine, as you may need to adjust your insulin dose.
You should not take phentermine if you have a history of heart disease, stroke, congestive heart failure, or uncontrolled high blood pressure. You also shouldn’t take it if you have glaucoma, hyperthyroidism, or a history of drug abuse, or if you are pregnant or nursing.
What else you should know: Phentermine is an amphetamine. Because of the risk of addiction or abuse, such stimulant drugs are “controlled substances,” which means they need a special type of prescription.
Phentermine and topiramate (Qsymia)
How it works: Curbs your appetite.
Qsymia combines phentermine with the seizure/migraine drug topiramate. Topiramate causes weight loss in several ways, including helping you feel full, making foods taste less appealing, and burning more calories.
Approved for long-term use? Yes. Qsymia has much lower amounts of phentermine and topiramate than when these drugs are given alone.
Side effects: The most common side effects are tingling hands and feet, dizziness, altered sense of taste, insomnia, constipation, and dry mouth.
Serious side effects include certain birth defects (cleft lip and cleft palate), faster heart rate, suicidal thoughts or actions, and eye problems that could lead to permanent vision loss if not treated.
Women who might become pregnant should get a pregnancy test before taking Qsymia, and should use birth control and get monthly pregnancy tests while on the drug.
You also shouldn’t take Qsymia if you have glaucoma, hyperthyroidism, heart disease, or stroke. Get regular checks of your heart when starting the drug or increasing the dose.
What else you should know: If you don’t lose at least 3% of your weight after 12 weeks on Qsymia, the FDA recommends that you stop taking it or that your doctor increase your dose for the next 12 weeks — and if that doesn’t work, you should gradually stop taking it.
How it works:Semaglutide working by imitating an intestinal hormone that stimulates insulin production, lowering your appetite and making you feel full
Semaglutide was initially approved as a treatment of type 2 diabetes and is prescribed for that use under the names Ozempic and Rybelsus. As Wegovy, it is specifically for treatment of obesity.
Approved for long-term use? Yes.
Side effects include abdominal cramping, constipation, vomiting, passing gas, headache, fatigue, and gastro reflux.
These side effects are generally mild and temporary.
In rare cases, issues involving the kidney as well as blurred vision have occurred. Semaglutide has been linked with instances of disease of the pancreas (pancreatitis). Get medical help right away if you develop symptoms of pancreatitis, including: severe stomach/abdominal pain, nausea/vomiting that doesn’t stop.e to manage your weight. Ceasing to take it could lead to regaining most of the lost weight.
You should also follow a low-calorie diet and exercise program.
Weight loss pills and supplements
1. Garcinia cambogia extract
Garcinia cambogia became popular worldwide after being featured on “The Dr. Oz Show” in 2012.
It’s a small, green fruit shaped like a pumpkin. The fruit’s skin contains hydroxycitric acid, the active ingredient in garcinia cambogia extract, which is marketed as a diet pill.
How it works: Animal studies show that it can hinder a fat-producing enzyme in the body and increase serotonin levels, potentially helping to reduce cravings (1Trusted Source, 2Trusted Source).
Effectiveness: In one meta-analysis, researchers explored four electronic research databases to investigate the effectiveness of herbal medicines, including garcinia cambogia.
In a total of 54 randomized controlled trials in healthy adults with overweight or obesity, the authors found no difference in weight or body fat percentage between the garcinia cambogia group and the placebo group (3Trusted Source).
A 2020 review that looked at eight trials on garcinia cambogia found that, on average, it caused weight loss of about 3 pounds (1.34 kg) (4Trusted Source).
Side effects: While it’s widely agreed that garcinia cambogia is safe to take in recommended amounts, studies within the last few years have pointed to some serious side effects.
A 2018 study documented four cases of women who experienced acute liver failure after taking weight loss supplements containing garcinia cambogia (5Trusted Source).
Additionally, hepatotoxicity, or liver impairment, and some episodes of mania have also been reported in conjunction with taking garcinia cambogia (6Trusted Source, 7Trusted Source).
Even though garcinia cambogia may contribute to modest weight loss, the effects are quite small and may not be noticeable.
Hydroxycut has been around for more than a decade and is one of the most popular weight loss supplements in the world.
The brand makes several products, but the most common is simply called “Hydroxycut.”
How it works: It contains several ingredients claiming to help with weight loss, including caffeine and a few plant extracts such as green coffee extract, which we’ll talk more about later.
Effectiveness: A 2011 meta-analysis of five clinical trials found that supplementation with C. canephora robusta, or green coffee extract, one of the key ingredients in Hydroxycut, led to about a 5.5-pound (2.47-kg) weight loss compared to the placebo .
Side effects: If you are sensitive to caffeine, you may experience anxiety, jitteriness, tremors, nausea, diarrhea, and irritability.
Hydroxycut products were removed from shelves as a result of cardiovascular risks in 2004 and hepatotoxicity in 2009 (10Trusted Source).
Acute liver injury has also been connected with using Hydroxycut supplements .
There are few large-scale studies on this supplement and no data on its long-term effectiveness. More research is needed to determine effectiveness and safety concerns.
3. Green coffee bean extract
Green coffee beans are simply coffee beans that haven’t been roasted.
They contain two substances believed to help with weight loss: caffeine and chlorogenic acid.
How it works: Caffeine can increase fat burning, and chlorogenic acid can slow the breakdown of carbohydrates in the gut.
Effectiveness: Several human studies have shown that green coffee bean extract could help people lose weight.
A meta-analysis of all the current randomized control trials on green coffee bean extract’s effect on obesity found that the supplement has a significant impact on minimizing body mass index (14).
Other benefits: Green coffee bean extract may help lower blood sugar levels and reduce blood pressure. It is also high in antioxidants (15Trusted Source, 16Trusted Source, 17Trusted Source, 18Trusted Source).
Side effects: It can cause the same side effects as caffeine. The chlorogenic acid it contains may also cause diarrhea, and some people may be allergic to green coffee beans.
Green coffee bean extract may cause modest weight loss, but keep in mind that many of the studies that have found this have been industry-sponsored.
Caffeine is the most commonly consumed psychoactive substance in the world
It is found naturally in coffee, green tea, and dark chocolate and is added to many processed foods and beverages.
Because caffeine is thought to be a metabolism booster, companies commonly add it to commercial weight loss supplements.
How it works: One study discussed the effect of caffeine on regulating body weight by increasing energy expenditure — essentially meaning you burn more calories via increased fat breakdown as well as through a process of body heat production called thermogenesis (21Trusted Source).
Effectiveness: Some studies show that caffeine can cause modest weight loss in humans
Side effects: In some people, high amounts of caffeine can cause anxiety, insomnia, jitteriness, irritability, nausea, diarrhea, and other symptoms. Caffeine is also addictive and can reduce the quality of your sleep (24).
There is no need to take a supplement or a pill containing caffeine. The best sources are quality coffee and green tea, which also have antioxidants and other health benefits
Caffeine could help boost metabolism and enhance fat burning in the short term. However, a tolerance to the effects may develop quickly.
5. Orlistat (Alli)
Orlistat is a pharmaceutical drug sold over the counter under the name Alli and via prescription as Xenical.
How it works: This weight loss pill works by inhibiting the breakdown of fat in your gut, meaning that you take in fewer calories from fat.
Effectiveness: A 2003 meta-analysis of studies found that people taking orlistat for 12 months in combination with lifestyle changes saw a 2.9% greater weight reduction than the placebo group
Other benefits: Orlistat has been shown to reduce blood pressure slightly and may reduce the risk of developing type 2 diabetes when used alongside lifestyle changes
Side effects: This drug has many digestive side effects, including loose, oily stools; flatulence; and frequent bowel movements that are hard to control. It may also contribute to deficiency in fat-soluble vitamins such as vitamins A, D, E, and K.
Following a low fat diet while taking orlistat is often recommended to minimize side effects. Interestingly, a low carb diet (without medication) has been considered as effective as orlistat and a low fat diet combined.
Both diets were as effective for weight loss but showed no significant differences in blood sugar and blood lipid levels. However, orlistat combined with a low fat diet was more effective at lowering blood pressure
Orlistat, also known as Alli or Xenical, can reduce the amount of fat you absorb from food and help you lose weight. It has many side effects, some of which are highly unpleasant.
6. Raspberry ketones
Raspberry ketone is a substance found in raspberries that is responsible for their distinct smell.
A synthetic version of raspberry ketones is sold as a weight loss supplement.
How it works: In isolated fat cells from mice, raspberry ketones increase the breakdown of fat and increase levels of a hormone called adiponectin, which is believed to be related to weight loss
Effectiveness: There are very few studies on raspberry ketones in humans, though one 2013 study looked at raspberry ketones along with some other ingredients and found a potential 2% increase in weight loss over 8 weeks when compared with a placebo
One mouse study using massive doses showed some delay in weight gain
However, high doses of raspberry ketones were also associated with higher blood sugar levels and higher levels of ALT, a liver enzyme, indicating liver dysfunction.
It’s unknown whether these effects would translate to humans. More research is necessary to determine any benefits and risks.
Side effects: They may cause your burps to smell like raspberries.
There is no evidence that raspberry ketones cause weight loss in humans, and the rat studies that suggest they may work used massive doses. More research is needed.
Glucomannan is a type of fiber found in the roots of the elephant yam, which is also called konjac.
How it works: Glucomannan absorbs water and becomes gel-like. It “sits” in your gut and promotes a feeling of fullness, helping you eat fewer calories
Effectiveness: One clinical trial showed that taking glucomannan for 60 days could lower body weight among participants with overweight, but only if they were consistently taking the supplement
Other benefits: Glucomannan is a fiber that can feed the friendly bacteria in the intestine. It can also lower blood sugar, blood cholesterol, and triglycerides and works effectively against constipation
Side effects: It can cause bloating, flatulence, and soft stools and can interfere with some oral medications if taken at the same time.
It is important to take glucomannan about half an hour before meals, with a glass of water.
Studies show that the fiber glucomannan, when combined with a healthy diet, can help people lose weight. It also leads to improvements in various health markers.
Meratrim is a relative newcomer on the diet pill market.
It’s a combination of two plant extracts — Sphaeranthus indicus and Garcinia mangostana — that may change the metabolism of fat cells.
How it works: It claims to make it harder for fat cells to multiply, decrease the amount of fat they pick up from the bloodstream, and help them burn stored fat.
Effectiveness: Very few studies about Meratrim exist. One study involved 60 people with obesity placed on a strict 2,000-calorie diet and increased physical activity, with either Meratrim or a placebo.
After 8 weeks, the Meratrim group had lost 11 pounds (5.2 kg) and 4.7 inches (11.9 cm) off their waistlines
Another study suggested that Meratrim had long lasting effects on appetite suppression
Side effects: No side effects have been reported.
One study showed that Meratrim caused weight loss and had a number of other health benefits. However, the study was industry-sponsored, and more research is needed.